Authorities in New Zealand have charged the self-avowed white supremacist who killed 51 worshippers at two Christchurch mosques back in March with terrorism.

The single charge filed Tuesday against Australian Brenton Tarrant is the first of its kind under New Zealand's Terrorism Suppression Act, which was passed in 2002 in the wake of the al-Qaida-led terrorist attacks on New York and Washington, D.C. the previous year. Prosecutors have also charged him with an additional count of murder over a worshipper who died in the hospital earlier this month, along with two additional counts of attempted murder, bringing that number to 40.

Up to 200 family members of the victims and survivors of the attack were informed of the new charges at a private meeting with police.

The 28-year-old Tarrant live-streamed the March 15 shootings at the al-Noor and Linwood mosques on Facebook from a head-mounted camera.

He is currently being held at a maximum security prison where he was ordered to undergo psychiatric tests to determine if he is mentally fit to stand trial. His next court date is June 14.

The 28-year-old Tarrant e-mailed a lengthy white nationalist manifesto to more than 30 recipients just minutes before the attacks - including Prime Minister Jacinda Ardern - in which he allegedly denounced Muslims and called immigrants 'invaders.'